Electromechanical transducers have been widely used in the acoustic industry to vibrate the cone of a loudspeaker and generate desired sound frequencies. Such transducers rely on the Lorentz forces generated when a coil of wire conducting a current is subjected to a magnetic field. A derived version of Lorentz's law provides a relationship between the force, current, and magnetic field:F=l(I×B)  (1)
Where F is the force, I is the current, l is the length of wire through which the current is flowing, and B is the magnetic field strength. Since the force vector is calculated as a cross product of the current vector and the magnetic field vector, the force vector will have a direction that is perpendicular to both the current direction and the magnetic field direction.
The coil of wire that conducts the current I and responds to the generated force when subjected to a magnetic field is commonly known as a voice coil in the field of audio engineering. Linear motor designs also often use the terminology of “voice coil” when describing the coil of current-carrying wire subjected to a magnetic field for the purpose of generating a force.
The voice coil is commonly wrapped in a circular direction and placed some distance away from a magnet with a given polarity, while an opposite polarity magnet is positioned somewhere on the outside of the wrapped coil. The magnetic field generated between the two opposite magnet polarities passes through the coil of wire and causes the voice coil to move up or down. This design is widely used for loudspeakers and other sound-generating devices. Although widely used and fairly inexpensive to manufacture, the amount of force that can be generated for a given current is limited.